Nestable container wrapping



April 16, 1963 J. w. HARRISON NESTABLE CONTAINER WRAPPING Filed Dec. 30,1960 W? %b FIG. 5

1 11111111111. III/III I N H ll FIG. 5

United States Patent 3,0$5,375 NESTABLE (IONTAlNER WRAPPING John W.Harrison, Winchester, Mass, assignor to W. R. Grace 8: (30., Cambridge,Mass, a corporation of Connecticut Filed Dec. 3t), 1960, Ser. No. 79,8136 Claims. (Cl. 53-30) This invention relates to a method of enclosing anobject within a protective wrapping or covering and more particularly toa method of enclosing a container within a protective wrapping orcovering that closely conforms to the interior of said container. Thisinvention also relates to the protectively wrapped container produced bythe method of this invention.

Specifically this invention is concerned with covering containers sothat the inner covering material closely conforms to the inner surfacesof the container so that little air space exists between the innersurface and the covering.

In packaging open topped containers it has been the practice heretoforeto enclose the containers within a loose bag or a loose fitting overwrapof transparent material. Another method of packaging such containers isto tightly cover the object with the wrapping or covering material. Bothmethods have disadvantages. The loose fitting covering is unattractive.The tight fitting covering, while attractive, does not permit thenesting of one packaged container within another packaged containersince the tight covering stretches over and closes the open top of saidcontainers.

It is among the objects of this invention to provide a covering for theinner surfaces of a container which covering is transparent, clear,wrinkle-free, and closely conforms to the inner surfaces of thecontainer. It is also an object to provide acovering for both the innerand upper surfaces that will permit nesting of the containers wheretheir shape so permits.

Other and further objects, advantages and features of the invention willbecome apparent to those skilled in the art from the followingdescription taken in conjunction with the accompanying drawings showinga specific embodiment of the present invention and in which:

FIGURE 1 is an elevational view in section of a container completelycovered with a transparent protective material according to the presentinvention.

FIGURES 2-5 are elevational views in section disclosing various steps inthe method of forming the covered container.

Referring to the drawings and in particular to FIG- URES 2-5 whichdisclose the method of this invention for forming a tight-fittingcovering for containers, there is shown a bottom mandrel designatedgenerally as numeral 11 consisting of an outer ring 12 and a flatcircular disc 13 which fits within said ring: Both the ring and the discare supported from below with the ring riding on a cam (not shown) whichpermits the ring to be moved below the level of the disc as shown inFIGURE 4.

A sheet of heat shrinkable film 21, larger than the overall outersurface dimensions of the container, is placed over the bottom mandrel.A container, e.g., an aluminum pan generally designated as 15 having acircular bottom wall 16 and an outwardly inclining sidewall 17 whichsidewall has a lip 18 on its upper edge is placed over said sheet offilm 21 and pushed down into said bottom mandrel which is shaped toaccommodate said container. The entire lower or outer surface of saidcontainer, i.e. the underside of the bottom wall, side wall and lip isin contact with said film and fits into the lower mandrel and only theedge of said film sheet 21 protrudes above said mandrel. Hot air isdirected against the protruding film Patented Apr. 16, 1963 See edgecausing it to shrink and in so shrinking to be drawn in and over the lipof said container as shown in FIGURE 3. Heat is applied to the edge ofthe film untilthe film has tightly shrunk over the lip and upper portionof the side wall.

A second sheet of shrinking film 22 large enough to both cover theentire upper or inner surface area of the container and to have anexcess of film extending beyond the edge of said container is placedover the top of said container. An upper mandrel 23 shaped so as toconform to the inner surface of said container as shown in FIG- URE 4 isbrought down by suitable means (not shown) into the cavity of thecontainer thereby causing the second film sheet to conform to the innersurface of said container. The excess film extending over the lip of thesidewall is heat shrunk under the lip as shown in FIGURE 5 making anairtight seal. The upper mandrel is re moved and heat is applied lightlyto the entire covered container to remove any wrinkles in the filmcovering. The wrinkles may be shrunk out of the covering without thefilm pulling very far from the internal surface of the container becausethe air-tight seal at the top of the sidewall prevents air from enteringbetween the film and the pan. It is possible to reverse the order ofapplying the film sheets, e. g., first covering the top or inner surfaceof the container and subsequently covering the lower or outer surface ofthe container. The covered container with wrinkles removed is shown inFIGURE 1. This package is transparent, wrinkle-free, attractive andpermits one packaged container to be stacked within a like packagedcontainer. The types of containers that may be packaged according tothis invention are quite varied and include but are not limited tometal, glass and plastic containers which may be square, rectangular,circular, oblong or almost any geometrical shape. The bottom wall neednot be flat but may be curved, ridged, etc. The sidewalls may bestraight, inclined or curved and the upper edge may terminate in a bead,flange or other projection or may have no projection.

Any heat shrinking plastic film that does not melt or decompose at thetemperature required for heat shrinking may be employed as a coveringmaterial in this invention. Examples of such film materials include butare not limited to heat shrinkable, irradiated biaxially orientedpolyethylene, oriented polypropylene, oriented copolymers of vinylidenechloride, e.g. saran films, oriented polyvinyl chloride and orientedpolyethylene terephthalate.

With some films there may be a slow leakage of air through the filmallowing the upper film sheet to pull away from the inner surface of thecontainer where it had formerly been held by atmospheric pressure. Thiswill not be serious where the containers are nested together. It can,however, be prevented by employing film materials that are relativelygas impermeable, or laminated films that are gas impermeable or bycoating a film with a gas impermeable coating.

The most convenient heat source for shrinking the film is hot air,although other heat sources may be employed, e.g., radiant heat, etc.

While for many purposes it will be desirable to cover both sides of thecontainer in the manner heretofore described, in many instances it willbe only necessary to cover the inner surface of the container.

Although the applicant has described a particularly suitable method ofsecuring the peripheral edge of the film sheets to the container, othermethods may be employed to seal the film sheet edges to the top of thecontainer, e.g. adhesives, heat seals, etc.

The invention described in detail in the foregoing specification issubject to changes and modifications without departing from theprinciple and spirit thereof. The

terminology used is for purpose of description and not of limitation,the scope of the invention being defined in the claims.

I claim:

1. A method of protectively packaging an open-topped container whichcomprises covering the inner surfaces of said container with a sheet ofheat shrinkable film material and causing said sheet to conform to theinner surfaces of said container, sealing the unconformed peripheralportion of the film sheet along and to the top of said container, andthen heat shrinking the film sheet within the container so as to tightenthe film while maintaining said sheet in substantial conformity with theinner surfaces of said container.

2. A method of protectively packaging an open-topped container whichcomprises covering the inner surfaces. of said container with a sheet ofheat shrinkable material and causing said sheet to conform to the innersurfaces of said container, heat shrinking the unconformed peripheralportion of the film sheet protruding above the container causing it toshrink over and around the top edge of the container so as to be lockedto said container and so as to form a tight seal around the top edge ofsaid container, and then heat shrinking the film Within the container totighten the shrinkable sheet material while maintaining said sheet insubstantial conformity with the inner surfaces of said container.

3. A method of packaging an open-topped container which comprisesplacing a sheet of heat shrinkable film material larger than the totalinner surface area of the container over the top of said container,causing the film sheet to conform and to cover the inner surfaces ofsaid container, applying heat to excess unconformed film ex tendingabove the top of said container causing it to shrink over and under thetop of said container so as to become locked to and form a tight sealabout said container, and then heat shrinking the film within thecontainer to tighten the film while maintaining said sheet insubstantial conformity with the inner surfaces of said container.

4. A method of packaging an open-topped container which comprisescovering the outer surfaces of said container with a first sheet of heatshrinkable film material, sealing the edge of said first film sheetalong the top of said container, covering the inner surfaces of saidcontainer with a second sheet of heat shrinkable film material causingsaid second sheet to conform to the inner surfaces of said container sothat substantially no air space exists therebetween, sealing theunconformed peripheral portion of said second film sheet along and tothe top of said container, and then heat shrinking both film sheets totighten the film, While maintaining said second film sheet insubstantial conformity with the inner surfaces of said container.

5. A method of packaging an open-topped container which comprisescovering the outer surfaces of said container with a first sheet of heatshrinkable film, heat shrinking the peripheral edge of said first filmsheet over the top of said container locking said film sheet to saidcontainer, covering the inner surfaces of said container with a secondsheet of heat shrinkable material causing said second sheet to conformto the inner surfaces of said container so that substantially no airspace exists therebetween, heat shrinking the unconformed peripheralportion of the film sheet protruding above the top of the containercausing it to shrink over and around the top edge of the container so asto become locked to said container and so as to form a tight seal, andthen heat shrinking the film sheets to tighten same, while maintainingsaid second sheet in substantial conformity with the inner surfaces ofsaid container.

6. A method of packaging an open-topped container composed of inner andouter surfaces which comprises covering the outer surfaces of saidcontainer with a first sheet of heat shrinkable film material'largerthan the total outer surface area of said container, heat shrinking theperipheral edge of said first sheet protruding above the top of saidcontainer over the top of said container, locking said film sheet tosaid container, placing a second sheet of heat shrinkable film materiallarger than the total inner surface area of said container over the topof said container, causing said second film sheet to conform toand coverthe inner surfaces of said container so that substantially no air spaceexists therebetween, applying heat to the excess unconformed filmextending above the top of the container causing said film to shrinkover and under the top of said container so as to become locked to andform a tight seal about said container, and then heat shrinking the filmsheets to tighten same, while maintaining said second sheet insubstantial conformity with the inner surfaces of said container.

References Cited in the file of thispatent UNITED STATES PATENTS 668,048McCarthy Feb. 12, 1901 1,618,989 McCumpsey Mar. 1, 1927 1,856,694DeCorrevont May 3, 1932 1,905,356 West Apr. 25, 1933 2,012,127 GriffithAug. 20, 1935 2,013,865 Sloan Sept. 10, 1935 2,210,509 Strauch Aug. 6,1940 2,402,943 Bogoslowsky July 2, 1946 2,668,403 Rumsey Feb. 9, 19542,672,981 Colgren Mar. 23, 1954 2,754,959 McCarty July 17, 19562,775,345 Pingrey Dec. 25, 1956 2,783,599 Weikut Mar. 5, 1957 2,801,180Rumsey July 30, 1957 2,942,390 Lerner June 28, 1960 2,976,655 DreyfersMar. 28, 1961 3,024,579 Stockhausen et a1. Mar. 13, 1962 3,034,271Carpenter et a1. May 15, 1962

1. A METHOD OF PROTECTIVELY PACKAGING AN OPEN-TOPPED CONTAINER WHICHCOMPRISES COVERING THE INNER SURFACES OF SAID CONTAINER WITH A SHEET OFHEAT SHRINKABLE FILM MATERIAL AND CAUSING SAID SHEET TO CONFORM TO THEINNER SURFACES OF SAID CONTAINER, SEALING THE UNCONFORMED PERIPHERALPORTION OF THE FILM SHEET ALONG AND TO THE TOP